


Wrong Size

by its_noma



Category: Shall We Date?: Obey Me!
Genre: Anal Fingering, Anal Sex, Cosplay, Crossdressing, F/M, Femdom, Pictures, Pranks, Riding, Strap-Ons, fem!reader - Freeform
Language: English
Status: Completed
Published: 2020-07-04
Updated: 2020-07-04
Packaged: 2021-03-04 01:54:39
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,304
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24595615
Author URL: https://archiveofourown.org/users/its_noma/pseuds/its_noma
Summary: “Pleasetry it on,” you beg before he can object. You press it further into his chest. “Just this once!”Leviathan stares at you with growing shock before it turns into something akin to disgust. You try giving him your best pleading look to try and convince him, but that only seems to make his disdain worse.“You look like a gross pervert right now, MC.”When Leviathan orders a cosplay for you in the wrong size, you try your best to make the most out of the situation.
Relationships: Leviathan (Shall We Date?: Obey Me!)/Reader, Leviathan/Main Character (Shall We Date?: Obey Me!)
Comments: 5
Kudos: 229





	Wrong Size

**Author's Note:**

> I've had this idea in my head for at _least_ two weeks now. Thank gods I've gotten over my writer's block and can get this out of my system! I'm sure there are probably plenty of fics similar to this one, but I haven't read any of them, so if it's similar to someone else's then I apologize!
> 
> I was listening to a lot of songs while writing this, but Kradness and UN:C's cover of Reol's [Gigantic O.T.N.](https://youtu.be/vUspPHa8SN8) is what I finished on. The uniform Leviathan wears is based off [this](https://www.amazon.com/Classic-Japanese-Uniform-Cosplay-Costumes/dp/B07FDLQBQC).

Cosplaying has never been your thing, but after making a pact with Leviathan, it’s become somewhat of a norm for you. Leviathan seems to think that, for whatever reason, you’re his cosplay partner now, so almost every week he has something new for you to try on. You comply solely because he’s usually cosplaying something that matches, so you’re not alone.

Nothing he presents you is terribly outlandish either. The only weird cosplay was Ruri-chan, which is unsurprising since she’s the protagonist of his favorite anime, though it had been… _really_ awkward just standing there and having him ramble to you, red-faced, about facts from the anime you didn’t understand.

But everything else has been fine. Which is why, when Leviathan drags you to his room after classes are over to try a new cosplay that just arrived from Akuzon, you go along willingly. You wonder what he has in store this time.

“I gave your weird ‘Vocaloids’ a listen,” Leviathan tells you. “They’re… _okay,_ for something a normie would listen to.”

You take a seat on the ottoman beside his bathtub. So you’re going to be cosplaying…a Vocaloid this time? Probably Miku. Knowing Leviathan, he took a liking to her immediately.

“Okay,” you say.

He huffs as he begins unboxing the cosplay. True to form, on the very top is the ever-so-popular V2 outfit of Hatsune Miku in all its grey, black, and teal glory. You personally prefer her newer V4 look, but this isn’t bad.

“Yeah,” Leviathan continues, “so I thought…um…well, I ordered a Miku cosplay!”

You nod. “I can see that. I thought I told you I liked Gumi more though?”

His cheeks are already flushed, but now they grow redder. “I—duh! I know! But it was really hard to find a good one!”

That’s hard to believe coming from such a hardcore otaku like Leviathan—who has done some pretty crazy stuff in the name of merch and the like—but you don’t push it. He already looks embarrassed enough.

“Who are _you_ cosplaying then? Kaito?” you inquire.

“Duh,” he answers. He reaches under the Miku cosplay and presents to you KAITO’s. “ _You’ll_ have to wear a wig, but I can get away without one since my hair is similar to his.”

“Purple and blue aren’t the same though.”

“Whatever!”

Leviathan grabs the Miku cosplay and tosses it over to you. You catch it, turning it over in its plastic packaging. It looks well-made.

“I also ordered something else,” he says.

You set the Miku cosplay off to the side. Another cosplay? Leviathan rarely orders more than a single pair of cosplays for you two, so this has your interest piqued. Maybe another Vocaloid cosplay? Gumi—and probably Gakupo—are off the table, but maybe he got a Rin and Len set?

“This seller was a pain to negotiate with, but in the end I got it cheaper than he was originally selling!” Leviathan explains, lifting from the box what looks to be…a schoolgirl uniform? “ _And_ it’s high quality!”

He must be way more excited about this than the Vocaloid cosplay if he’s already taken the uniform out of its packaging. You giggle as he nearly _skips_ over to you, urging you to stand so he can hold it up to you.

“Based on the new measurements you sent me”—you raise a brow—“it should be a _perfect_ —wait, why is this so big?”

Confused, you ask, “What new measurements?”

“The ones you texted me last week!” he elaborates. “You know how important it is to me to get the proper size, so you texted me updated measurements from the ones I’d been using before! Though I have to admit, I was surprised when they were so different…”

Huh? You never texted Leviathan updated measurements. The ones you gave him a while ago have worked just fine this entire time. Why would you send him different ones?

You whip out your D.D.D. and pull up your texts with Leviathan. Nowhere is there a conversation from last week about measurements, and after you show him he takes out his own D.D.D. to compare.

And there it is. The conversation is on his, but not yours. How the…?

“Wait, I was hanging out with Asmo that night,” you remember.

Flashbacks to spending a rather relaxing evening with Asmodeus come back to you. You remember having to go to the bathroom, though you hadn’t taken your D.D.D. with you… 

“Well, shit,” you mutter. “He must’ve texted you and then deleted the conversation.”

Leviathan puts away his D.D.D. with an annoyed exhale through his nose. “Great. _Just great._ This is so unfair! Now I’ll have to return it and order a new one! And the seller might not give me a discount this time…”

You shake your head, taking the uniform from him. “Maybe it just looks bigger than it actually is? No harm in me trying it, right?”

“If you wear it, then we can’t return it,” he explains. “That’s the policy the asshole set up.”

“Oh.”

“Yeah.”

Well, that’s a bummer. Leviathan walks back over to the box to begin taking the KAITO cosplay out with a dejected sigh. You hold up the uniform one last time, ready to admit defeat—

And then stop.

Wait a minute.

“Levi,” you say, and he hums. “Stand still for a sec.”

He turns towards you, confused as you press the uniform against him. “What the? What are you doing?”

“It looks like it’ll fit _you_ ,” you realize.

The sudden image of Leviathan wearing this uniform makes you bite your lip. All of the cosplays _he’s_ worn with you have been the boring male counterpart, but _this_?

“ _Please_ try it on,” you beg before he can object. You press it further into his chest. “Just this once!”

Leviathan stares at you with growing shock before it turns into something akin to disgust. You try giving him your best pleading look to try and convince him, but that only seems to make his disdain worse.

“You look like a gross pervert right now, MC.”

“Oh, _come on_ ,” you cry. “I never complain about the cosplays you have _me_ wear!”

“Why would you? I’ve never forced you to wear something weird!” he exclaims. You raise an unamused brow at him. “Okay, nothing _too_ weird!”

“Just this once,” you beg.

Leviathan bites his bottom lip, looking between your face and the uniform with growing uncertainty as his face reddens. You think he’s going to call you a freak and kick you out of his room, but you’re pleasantly surprised when he slowly nods.

“Fine,” he caves, voice small. “But just this once!”

You beam. “Of course!”

He runs off to the bathroom to change. You can’t wait. Just the thought of Leviathan in that schoolgirl uniform…your mouth waters.

Mind made up, you make a quick visit to your room to find your strap and lube. This is a once in a lifetime opportunity. You’re not going to let it pass you by!

He’s still in the bathroom when you return. How long does it take to change in a simple uniform? You take a seat on the ottoman, jolting when you accidentally sit on the Miku cosplay you forgot was still there.

An idea comes to you.

When Leviathan returns, face the reddest you’ve ever seen it—briefly you’re worried he’ll pop a blood vessel—he stops dead in his tracks when he sees you. You shift on the ottoman to face him.

Your eyes widen, looking him up and down with hungry eyes. “You look so cute!”

The navy uniform looks even _better_ on him than you could’ve ever imagined, and it fits _perfectly._ You’ll have to thank Asmodeus later. Even if it was just a prank, it’s the best prank played on you in your _life._

He stutters as he grumbles, “Sh...shut up…”

He seems frozen in place, so you take it upon yourself to stand and walk over to him. You hadn’t imagined the weird boots Miku wears to be so…well, they’re not _uncomfortable,_ but they _are,_ without a doubt, foreign. But aside from that, the cosplay is fine. You’d forgone the wig for now, an observation Leviathan mutters as you approach.

“It’ll get in the way,” you explain, and before he can ask, you pull him down into a kiss.

He makes a surprised noise. You push against him until his back hits the wall behind him, smiling against his lips as he gasps.

Before you can lick into his mouth, he pulls back with a startled look. “What—I—”

“It isn’t every day I get to see you wearing a skirt,” is the shitty excuse you give, grinning from ear to ear. “Don’t you think I’m allowed to take advantage of it?”

Leviathan looks at a loss for words, eyes looking around at anything but you. You like seeing him so embarrassed because of you; he really _is_ adorable.

He yelps when your hands find his hips. “Hey, what’re you—”

You begin pulling up the fabric of the skirt, licking your lips as more of his thighs are revealed. The skirt is just barely long enough to meet the thigh high socks he has on, but with it out of the way you can see the creamy skin underneath with perfect clarity. The ends of the socks grip his thighs with just the right amount of pressure… 

You’re about to touch the fabric covering his left thigh when he slaps your hand away. Surprised, you look up to see him, red-faced, with tears beading at the corners of his eyes. The sight only makes you hornier.

Before you can say anything, he sniffles, “You really _are_ a gross pervert…”

“You like it,” you quip, grinning as he looks away. “You do, don’t you? There’s no need to deny it. I won’t tell anyone.”

He shakes his head. Fickle, isn’t he? Whatever. You know how to get him to tell you the truth.

Lifting his skirt higher, you’re disappointed to see him still wearing boxers. It’d be weird to sell underwear with a schoolgirl uniform, you suppose, but _still,_ it would’ve been _perfect._

Taking them off will help salvage that.

“Wait, don’t!” Leviathan cries, but before he can stop you, his boxers are off and around his ankles on the floor. He buries his burning face in his hands. “You…you freak!”

You take one look at his cock and smirk. _You’re_ the freak, huh? Then—

“Why are you hard?” you ask.

Leviathan’s hands quickly push your hands away, yanking the skirt down to cover his shame. You giggle.

“I’m just teasing you,” you murmur, reaching up to caress his cheeks. “We can stop if you want.”

He leans into your touch. The tears from before now cascade down his cheeks, wetting your fingers. You wipe them away.

“No, I…” He fidgets, playing with the hem of the skirt bunched in his white-knuckled fists. “I…”

_Aha._ “You wanna keep going?”

He scrunches his eyes closed but nods. Smiling, you reach up and press a chaste kiss to his lips.

“Okay,” you say. “Turn around for me.”

You pull away, and he opens his eyes to look at you again, confused.

“Why?” he asks.

“Just do it.”

“Fine, fine…”

Leviathan slowly turns around, hands shaking as he places them on the wall. You flip up your skirt, revealing your strap, and press the colorful dildo up against his covered rear.

He shouts in surprise, pressing himself closer against the wall to get away from you. “What was that?!”

“A surprise.” You pull him back to you by the hips, flipping up his skirt. “Like it?”

“No! I—how did you even hide that?!” he squawks, looking back at you for all of two seconds before he squeezes his eyes shut. “Never mind! I don’t wanna know!”

You laugh. “I just hid it under the waist of my skirt, Levi.”

“O…oh.”

“Yeah.” You gently run the pad of your index finger along his left hip, reveling in the way he shivers. “But we don’t have to do it if you don’t want to.”

You let go of his hips for emphasis. Leviathan peeks his eyes open and glances back at you. Smiling, you raise your hands to show him you’re serious.

He swallows. “We don’t…uh, _have_ to stop…”

_Yes._

“You’re sure?” Your hands find his hips again, pleased when he pushes back into your touch. “If you don’t wanna stop now, there’s no backing out later.”

Leviathan bites his bottom lip. His eyes stray down to the strap between your legs, the blush that had been slowly lessening now burning bright with renewed fervor.

“I’m sure,” he whispers, voice cracking.

You press a kiss between his shoulder blades through his shirt. “Okay. I’ll take good care of you, Levi.”

“Don’t say it like that,” he mutters. “This is always embarrassing eno—”

He cuts himself off with a startled shout as you slide two fingers down between his cheeks, gently teasing his hole. You chuckle and apply more pressure just to watch him squirm.

But you’d rather tease him later when you’re not unbearably horny. You fish out your small bottle of lube from the tiny breast pocket Miku’s cosplay has, pouring almost all of its contents onto your fingers. When you return to Leviathan’s hole, he exhales a soft moan.

“Loosen up for me,” you instruct. “You’re too tense.”

“Can you blame me?” he retorts, but does his best to do as you say.

You roll your eyes as you begin pressing a finger inside. He’s unbelievably tight—more than usual, even—and so you have to take more time stretching him open, though you don’t mind. Feeling him squeeze around you is a pleasure all on its own. With every additional finger you add, that pleasure only heightens.

Leviathan seems to be enjoying it a lot too. You’re always disappointed with how _quiet_ he normally is when you two do this, but today he’s surprisingly loud. You love it. Each stroke against his walls has him whining, each kiss you press to his neck and shoulders eliciting a shaky sigh. When you reach around to wrap a hand around his cock, he _squeals._

“Someone’s sensitive today,” you comment, grinning.

He glares at you over his shoulder, but given the situation, it isn’t at all intimidating. “Sh-shut up! You’re just…taking too long!”

“Oh, am I?” Hesitant, he nods. “Okay. Let’s fix that.”

You pull your fingers out and grasp your strap. Using the excess lube on your fingers, you slick up the dildo and press the tip to his entrance.

He tenses up. “Wait!”

You stop. “What?”

“I…” He swallows, and you follow the movement. “I wanna…see you…” When you don’t respond right away, he splutters, “I mean! Never mind, that was weird, wasn’t it? Just pretend I never said anything, I—”

“No, no,” you interject, gently turning him around to face you. “That’s not weird at all.”

He sighs, relaxing against the wall.

You take his hand. “Here, let’s move.”

“Where?” he asks, but follows as you pull him towards the ottoman.

Taking a seat, you pat your lap.

He fidgets. “Oh, I don’t—”

“Come on,” you urge.

You take his hands and pull him down. He lets out a surprised yelp as he’s forced to step forward, tripping on one of the ottoman’s legs and tumbling down onto you. You catch him before the two of you can tumble onto the floor.

You smile as he finally settles into your lap. “Good boy.”

Leviathan glares but doesn’t say anything. You bring him closer, strap in hand as you bring it back to his hole.

He moans as you begin pushing it in, sinking into him inch by inch. “Ah…MC…”

“Just a little more,” you assure.

Finally you bottom out, Leviathan’s hips flushed against yours. He slumps against you, gasping into your shoulder. You rub comforting circles into his lower back.

“Can I move?” you ask.

He nods slowly. Your hands find his hips and lift him up before dropping back down again. Arms wrap around you as you do it again, Leviathan’s following whine loud in your ear.

“You’re so cute,” you coo, turning to press a kiss to his cheek. He shakes his head. “You _are_! The uniform looks _so_ good on you. No one else could ever compare, Levi.”

That has his lips curling. Hopeful, he asks, “Really?”

You nod. “Really.”

He giggles. You smile and kiss him, hips thrusting up. Leviathan gasps into your mouth. His arms tighten around you as your thrusts grow faster, dropping him down onto your cock harder and harder. His thighs quiver on either side of yours.

“MC,” he mewls after a few minutes, holding you closer. “I— _ah!_ —I’m—”

So soon? “Okay, baby. I’ve got you.”

You reach a hand down between your bodies.

You’re about to grab his cock when he gasps. “Wait! I don’t—your outfit—”

Huh? Oh, right, you’re still wearing the Miku cosplay.

“Right,” you say.

Changing tactics, you wrap your hand around his cock from over the skirt. He jolts as the cotton rubs against the sensitive skin of his cock.

Pulling away to look down, he stares in confusion. “Wha—”

“It’ll stop you from dirtying my outfit,” you tell him.

“But then I can’t return this one—”

“You’re already wearing it, so you can’t anyway.”

Leviathan’s brows furrow. “But—”

He gasps as you begin thrusting your hand, soon matching pace with your hips. He seems to forget what you’d been talking about as he pulls you close again. You don’t mind at all.

You kiss and bite at his neck, murmuring quiet encouragements as his hips lurch the closer he gets to coming. He shivers. It’s times like this where you wish you could feel how warm and tight he is. Maybe the Devildom has something like that? A strap that simulates how it feels for the one using it?

Your thoughts are interrupted as Leviathan’s body tenses up. His lips find your neck as he moans through the rapid jerks of his hips. You look down, biting your lip as you see the fabric of his skirt darken where his cum is spurting out.

“Good boy,” you praise as he slumps against you, boneless. “That was fun, wasn’t it?”

He huffs. “I guess…”

“It was,” you insist, laughing when he pulls away just enough to glare at you. “Come on! You enjoyed it!”

“You ruined the skirt,” he scowls. “Now I can’t return it!”

“You said you can’t if someone wears it, and you’re already wearing it.” You shrug. “That just means we can do this again, right?”

Leviathan stares at you, incredulous before he buries his face in your shoulder again, embarrassed. You laugh, patting his back.

You stay like that for a few minutes, letting Leviathan bask in the afterglow.

That is, until the shutter of a camera goes off.

You two snap to attention, heads whipping around towards the door. Mammon stands there grinning at the screen of his D.D.D. before he realizes that he’s been spotted.

“Oh shit,” he mutters, and then runs off.

Leviathan’s face is beet red as he shrieks, “You’re _dead,_ Mammon!”

“Now, now,” you chuckle, wrapping your arms around him before he can get up and run after him. “I’ll get him to delete it later.”

“Yeah, when it’s already been monetized, or whatever else he’s gonna do with it!” Leviathan frets.

You shake your head. Lucifer will probably punish Mammon before Leviathan even gets the chance. You’re not all that worried.

“Let’s do it again.”

“Is everyone in this house crazy?!”

But he doesn’t say no.

**Author's Note:**

> As always, thank you for reading!


End file.
